1. Field of the Invention
The invention relates to a flashlight, more particularly to an improved flashlight construction which is easier to assemble than the prior art.
2. Description of the Related Art
FIG. 1 is an exploded perspective view of a waterproof switching device disclosed in U.S. Pat. No. 4,940,860 by the applicant. FIG. 2 is a fragmentary sectional view of the waterproof switching device when incorporated in a flashlight. The conventional switching device is shown to comprise a switch assembly (10), a lamp socket assembly (15) and a coupling unit (17). The switch assembly (10) includes a generally cylindrical shaped body (11), an electrical switching element (12) and a switchplate (13). The body (11) has a first part (111) in the shape of a segmented cylinder and a second part (112) in the shape of a complementary segmented cylinder. The first and second parts (111, 112) have abutting surfaces which comprise sloping planes that incline longitudinally relative to an axis of the body (11) and that have a conforming sloping relationship so that the first and second parts (111, 112) sealingly engage each other. One end of the body (11) is provided with a blind bore which has an internally threaded surface (113). The lamp socket assembly (15) includes a conductive compression spring (151) which extends into an insulating envelope (152), and a conductive tubular lamp holder (153). The insulating envelope (152) extends into the rear end of the lamp holder (153). The rear end of the lamp holder (153) is formed with an external screw thread (1531) which engages the internally threaded surface (113) of the body (11). The front end of the lamp holder (153) is formed with an internal screw thread (1532) which engages the base of a lamp (154) so as to retain the lamp (154) thereat. The coupling unit (17) is a ring which has an outer peripheral surface that is formed with a screw thread (171). The screw thread (171) engages a corresponding screw thread formed on an inner wall surface of a barrel (18) of a flashlight. The coupling unit (17) is disposed inside the barrel (18) around the lamp holder (153) to connect electrically the barrel (18) and the lamp holder (153). The flashlight is further provided with a head assembly (19) which is mounted rotatably on a front end of the barrel (18). The lamp (154) extends into the head assembly (19). The head assembly (19) is controllably translatable along the barrel (18) when rotated with respect to the barrel (18) in order to achieve a variable focusing effect.
It should be noted that in the conventional flashlight, the switch assembly (10), the lamp socket assembly (15), the coupling unit (17) and the barrel (18) are connected by means of internal and external screw threads. The screw threads should be perfectly matched in order to ensure proper positioning of the lamp (154) and the lamp socket assembly (15) and to further ensure ease of adjustment of the head assembly (19) when varying the focusing of the flashlight. Improperly matched screw threads can seriously affect the quality of the flashlight. Furthermore, since the various components of the flashlight are assembled manually, improper engagement among the screw threads of these components usually occurs, thus necessitating the disassembly of the improperly assembled components and the repetition of the assembly procedure. This results in a waste of time and manpower.